As computing and processing technologies improve over time, there is a commiserate need for advances in memory technology as well. This is because the increase in speed of processors requires a similar increase in speed of memory components, such as DRAMS (Dynamic Random Access Memory), to boost overall system performance. For example, the target speed for LPDDR4X DRAM is up to 5.4 Gbps, while the target speed for LPDDR5 DRAM is up to 6.4 Gbps.
At the same time the target speeds of DRAM are increasing, the IO (Input/Output) interface supply (VDDQ) for DRAMs is also being reduced to reduce the dynamic power of the DRAM product. In the advance generations of DRAMs, the target VDDQ supply for DRAM products, such as for example, LPDDR4X DRAM is 0.6V to 0.4V and the target VDDQ supply for LPDDR5 DRAM is 0.5V to 0.3V.
The issue being addressed by the present disclosure is that as target speeds increase for memory technology, this leads to potential problems that arise for conventional output drivers, particularly in combination with the reduction of supply voltages for these circuits. One reason is because as the VDDQ supply may be near the threshold voltage of the output driving devices, this means that the output driver may present large variations in its drive. In addition, challenges exist for conventional output drivers associated with ensuring the linearity of the output driver impedance with respect to the output voltage. To address these problems, conventional output drivers would need to increase the size of the output driving devices. However, this leads to excessive design footprint requirements for the circuit design, as well as leading to excessive power requirements.
Therefore, there is a need for an improved approach to implement output drivers for memory technologies. In particular, there is a need for an improved approach to implement output drivers for memory components that can both handle the higher levels of target speeds of advanced memory designs, as well as the requirement for lower supply voltages.